Tuesday, February 10, 2009

One of the most daring series of flights, from any space exploration project has to be the early Pioneer launches. Between August 17th, October 11th, and November 8th, three very small probes were launched into deep space in an attempt to orbit the Moon and return images of the farside.

The initial probe names "Able", refer to the launcher which consisted of a Thor booster, and an Ablestar sustainer. "The original plan was for the spacecraft to travel for 2.6 days to the Moon at which time a TX-8-6 solid propellant motor would fire to put it into a 29,000 km lunar orbit which was to nominally last for about two weeks."

The historical context of these launches is very important: this project started launching less than 1 year from the first artificial satellite, placed in orbit on October 4th, 1957 ("October sky"), and only about 6 months after the first US satellite launch. This was a daring project because at a time when launching small payloads to orbit was a serious challenge, the goal was to launch a payload into solar orbit, then fire a small retro motor to catch lunar orbit. The complexity, the accuracy, and the risks involved in such a project are really appealing. This small team literally shot for the moon. The first launch was under the USAF, the next two were moved to NASA.

No launch was able to make lunar orbit, collide with the moon, or even enter solar orbit. However, the results were still impressive at times:

Pioneer 0 - Able 0 was destroyed during a rocket failure at 77 sec.Pioneer 1 hit a peak altitude of 113,800 km, but returned to earth after almost two days.Pioneer 2 hit a peak altitude of 1550 km due to an upper stage failure.